Rheostat



April 15, 1924. 1,490,334

J. F. LINDBERG RHEOSTAT Filed May 29. 1922 Ema flag 7 g 5 7 Patented Apr. 15, 1924.

UNITED STATES JOHN F. LINDBEBG, OF CHICAGO, ILLINOIS.

REEOSTAT.

Application filed May 29, 1922. Serial No. 564,307.

' the resistance is varied smoothly as distinguished from step by step variation thereof. -The rheostat of my invention includes a pluralit of resistance wires, and a current conducting brush preferably in the form of a metallic block that bridges said wires,

the brush and wires being relatively movable to shift the brush longitudinally of the wires. There is preferably, a carrier for the brush, and a spring upon the carrier for pressing the brush upon the wires.

In the preferred embodiment of the invention two parallel wires are wound upon the curved surface of a cylindrical drum which carries two binding sts, one'for one end of each wire, the ot er ends of the wires being dead ended. The brush is mounted upon an adjusting arm that is concentric with the drum, said arm carrying a spring that presses the brush radially inward upon both wires,.the brush thus serving as a circuit closer.

The invention will be more fully explained by reference to the accompanying drawing in which Fig. 1 is a side view of a rheostat made in accordance with the preferred embodiment of the invention, a form of circuit being diagrammatically illustrated;

Fig. 2 is a sectional view on line 22 of Fig. 1; Fig. 3 is a plan view; and Fig. 4

is a perspective view of the brush and the arm carrying the same.

Likeparts are indicated by similar characters of reference throughout the different The cylindrical mounting drum 1 has a base projection 2 which carries the binding posts 3 and 4 and is provided with holes 5 and 6 through which attaching screws may be passed.

Two uncovered resistance wires 7 and 8 are wound upon the cylindrical surface of the drum, these wires being preferably parallel and disposed in planes that are perpendicular to t c axis of the drum. One of 65 these wires terminates at one end in the the drum, isindicated at 21.

binding post 3 and the other at the other end in the binding post 4. A metallic hearing sleeve 13is co-axial with the drum and in it a shaft 14 is mounted to turn, this shaft being provided with a turning knob 15 at one end.' The other end of the shaft is formed with a threaded bore to receive the stem of a bolt 16 which also passes through ahole 17 in a switch arm 18. The bolt head 19 holds the switch arm in assembly with the shaft 14 and prevents this shaft from moving toward the knob side of the drum. Any means may be provided to prevent the shaft from moving toward the arm side of the drum, the thickening of the shaft being illustrated for this purpose.

The arm 18 is desirably formed of a piece of sheet metal that bulges away from the drum as indicated at 20 and is angularly extended to overlie the cylindrical surface of The sides of the arm are closely approached so as to afford a slideway therein for the mounting brush or block 22 that is preferably of metal. A spring 23, preferably of resilient wire, is anchored at one end to the portion of the arm which overlies the fiat side of the drum, this wire being continued through the hollow interior of the arm and thence outwardly to engage the outer end of the block 22, the spring serving to press the block against the wires.

The circuit illustrated in Fig. 1 includes an incandescent lamp 26, a battery 27, the contacting block or brush 22 and the portions of the wires 7 and 8 that are between this block and the binding posts 3 and 4, the balanceof the wires being" out of circuit. The portion of the wires that are between the' block 22 and the binding posts terminate in the resistance that is supplied to the lamp circuit to regulate the brilliance or heating effect of the lamp.

The rheostat of my invention is of particular service for regulating the flow of current through the filament of an audion bulb, though the invention is not to be limited to any particular use to which it may be put. The main advantage in the rheostat, as illustrated, is that the circuit which includes the resistance wires is not established through the contact arm or other moving parts except the block 22 so that no uncontrollable resistance such as-that due to loose joints can enter the circuit, a feature of much importance in the regulation of the inward upon said block to maintain it in -esistance in the filament circuit of an audion engagement with the resistance wires.

bulb.

While I have herein shown and particularly described the preferred embodiment of my invention I do not wish to be limited to the precise details of construction shown as changes may readily be made without departing from the spirit of my invention, but having thus described my invention I claim as new and desire to secure by Letters Patent the following 1. A rheostat including a cylindrical mounting drum; two binding posts upon the drum; two resistance wires disposed upon the cylindrical surface of'the drum, each having a binding post individual thereto and connected therewith; an arm having one portion facing a flat side of the drum and an angular portion overlying the cylindrical surface of the drum, said arm and drum being relatively rotatable upon the axis of the drum; acontacting block slidably mounted upon the angular portion of the arm and engaging both of said wires in the various ositions of said arm; and a spring carried y the arm and pressing radially 2. A rheostat including a cylindrical mounting drum; two resistance wires disposed upon the cylindrical surfaoe of the drum; an arm having one portion facing a fiat side of the drum and an angular portion overlying the cylindrical surface of the drum, said arm and drum being relatively rotatable upon the axis of the drum; a contacting block slidably mounted upon the angular portion of the arm and engaging both of said wires in the various positions of said arm; and a spring carried by the arm and pressing radially inward upon said block to maintain it in engagement with the resistance wires.

3. A rheostat including a cylindrical mounting drum; two resistance wires disposed upon the cylindrical surface of the drum; and an arm carrying a contact engaging both of said wires, said arm and drum being relatively rotatable upon the axis of the drum.

In witness whereof, I hereunto subscribe my name this 20th day of Ma A. D. 1922.

JOHN F. NDBERG. 

